JP2008500525A - A system for predicting and measuring turbulence upstream of aircraft. - Google Patents

Abstract

A system for anticipated measurement of turbulence upstream of an aircraft, placed on-board the aircraft, includes a lidar, an image detector, a first processing component, and a second processing component. The lidar transmits an optical beam toward a front of the aircraft and receives a backscattered optical beam. The image detector detects variations in wind speed based on the backscattered optical beam. The first processing component uses a first internal correction algorithm to calculate values of components of the wind speed. The second processing component uses a second external correction algorithm to deliver possible command signals to actuators of at least one aircraft control surface based on the calculated values of the components of the wind speed from the first internal correction algorithm.

Description

  The present invention relates to a system for predicting and measuring turbulence upstream of an aircraft. Throughout the following description of this application, an aircraft is considered to be, for example, an airplane.

  In passenger aircraft with more than 100 seats, the means for minimizing the effects of turbulence is to measure the response of the airplane once the airplane enters turbulence or when the wind reaches the airplane It is based on a plurality of sensors that make it possible to calculate the wind component. Minimizing the effects of turbulence usually reduces the structural load generated and the structure of the aircraft, reducing the load factor and angular velocity of the aircraft exposed to turbulence, and improving passenger comfort. This is achieved by reducing the stress applied to the. Measuring means located at the nose or tip of the aircraft make it possible to have an advanced phase with respect to the time of the wind hitting the wing. However, even for the largest airplane, the distance between its nose and its wing does not allow a forward phase of more than 100 ms. With regard to current actuator output speeds, it is not possible to obtain optimal efficiency based on the overall degree of control surface warpage and, therefore, specific laws that reduce load or improve passenger comfort. Absent. Such efficiency can be increased by installing faster actuators or by maintaining current actuators and measuring wind speed in front of the device. Sensor displays and methods currently used in civil aircraft can be found in numerous documents. For example, reference [1] at the end of the present specification can be cited (for example, see Patent Document 1).

It should be noted that the use of a rider to reduce the consequences when an aircraft encounters upright turbulence is described in reference [2] (see, for example, US Pat.
"Les avions de transport modernes et futures" by (Peyrat-Armandy, A, Teknea, pages 315-325, 1997). "Coherent lidar turbulence measurement for gust load alleviation" for mitigating gust loads by D. Loreide, RK Bogne, LD Ehernberger, H. Bagley (NASA-TM-104318, August 1996). “Imaging techniques and systems: riders” by PS Argall, RJ Sica (Encyclopedia of Imaging Science and Technology, J. Hornak, New York, Wiley 869-889, 2002). International Application Publication No. 2004/003626 Pamphlet German Patent No. 10316762 US Pat. No. 6,601,801

  In order to overcome the disadvantages of the known prior art document, the present invention uses lidar (LIDAR: “Light Detection and Ranging”) and uses conventional data (ADC: “airflow data computer”). (Air Data Computer) ”, IRS:“ Inertial Reference System ”, etc.), sufficient to enable operation by the flight control system of the airflow working surface being forward phased with respect to the system The purpose is to measure the wind speed in front of an aircraft at a certain distance.

  The present invention relates to a system that predicts and measures turbulence upstream of an aircraft and is located on board the aircraft, which transmits a light beam toward the front of the aircraft and is scattered A direct detection device associated with the lidar, for example a UV lidar, a control means for receiving the light beam, a first processing element using a first internal correction algorithm, and at least one aircraft control surface And a second processing element that uses a second external correction algorithm to transmit executable instructions to the actuators of the first actuator.

  The system of the present invention advantageously includes an optical transceiver and receiver.

The optical transceiver includes:
-Laser,
-Optionally a frequency multiplier,
-Obturators,
-Rotating mirror and prism system,
-Telescope,
A window processed for a selected laser frequency, and an optical fiber.

The receiver includes:
-Optical fiber,
-Fabry-Perot interferometer placed between the two optical lenses,
-Filters,
An image intensifier, and a processing element that executes the image detector and the first algorithm.

The system of the present invention differs from the invention described in reference [2], in particular by the following features:
-Direct detection (reference [2] is intended only for interference detection), and-correction of the influence of velocity in the axial direction of the turbulence and in the direction perpendicular to the axial direction. In recent experience, the effects of these components are firstly due to correction of further influences of the vertical component, and secondly, aircraft extension (Ref. [2] is intended only for correction of vertical velocity) Indicates that it will begin to be affected.

The system of the present invention has many effects:
-The use of an ultraviolet rider makes it possible to obtain better performance than with an infrared rider. The rider can thus be created by an infrared diode and a frequency multiplier or by an ultraviolet diode. Literature on rider technology is presented in [3].
The use of a direct detection system makes it possible to take advantage of the Mie and Rayleigh backscattering (aerosol and molecular backscattering). The measurement of clean air is thus made possible. Such direct detection is defined in reference [3].
-The use of very short rider command pulses (10 nanoseconds) makes it possible to obtain very small measuring volumes. Use a single laser with multiple point scans to obtain velocity data (Doppler lidar allows velocity data to be obtained only within the linear view of the laser). A possible scanning system is described in reference [4].
Integrating this rider into the aircraft makes it possible to obtain three components in the time-forward phase d / V, where d is the viewing distance and V is the airplane speed. The recovered speed is in the region where the aircraft passes upstream of itself at a distance of more than 500 feet. Thus, the measured value is representative of the turbulence encountered, assuming it is stationary over the period d / V.
-The use of wind speed data in combination with aircraft parameters makes it possible to determine the commands to be applied to the control surface.
-Reduce dimensional burden: The maximum load on the aircraft when encountering exceptional turbulence is reduced. In this way, it is possible to reduce the mass of the aircraft structure.
-Reduce fatigue load: When turbulence is encountered, the stress on the wing is reduced. As a result, the resulting stress corresponds to lowering the fatigue cycle and the lifetime of the structure is thus increased.
-Improving passenger comfort: In the present specification, the acceleration of the body response mode is reduced, so that when encountering small turbulence, the passenger is not affected by vibration.
The control law associated with the detection system may be an open-loop and closed-loop control law;
It is possible to adapt the most appropriate commands to achieve the expected control of the actuators of the aircraft flight control surface.

  As shown in FIG. 1, in the system of the present invention, a signal emitted by a rider that transmits a laser beam 11 forward and receives a backscattered beam 12, as well as a sensor 13 of an aircraft 14. The signal is input into a flight control computer 15 that provides commands to the flight control surface 16.

As shown in FIG. 2, these flight control surfaces 14 may thus be as follows:
The wing 20, which is a control surface for lateral control, which is a direction perpendicular to the roll or longitudinal direction, giving a moment with respect to the axis Ox (aircraft axis);
A tip edge flap 21 used at take-off and approaching and returning to the stalled position of the wing;
The rudder 22, which is a yaw control surface or rider, giving a moment with respect to the axis Oz;
The elevator 23, which is a pitch control surface or an elevator, giving a moment about the axis Oy;
A “spoiler” 24 which is mainly used to keep the airplane on the ground during landing and to increase the braking effect, and which can be used in flight for emergency landing;
-A flap 25 which is used at take-off and takes off outward to gain further lift at low speed;
-High speed control surfaces such as miniature TEDs ("Trailing Edge Devices") that can also be used for direct control of lift.

  In this figure, the position O is located at the center of the center of gravity of the airplane.

  As shown in FIGS. 3 and 4, the system of the present invention includes a rider 10 including an optical transmission / reception unit and a reception unit.

  The optical transceiver includes a laser 30, an optional frequency multiplier 31, an obturator 32, a rotating mirror and prism system 33, a telescope 34, and a window processed for the selected laser frequency. And an optical fiber 35.

  The receiving unit executes a Fabry-Perot interferometer 36 disposed between two optical lenses 37, a filter 37, an image intensifier 39, an image detector 40, and a first algorithm (internal connection). And a processing element 41.

The system of the present invention is connected to a flight control computer 42, which
Correct the speed 43 using the calculated wind speeds Vx, Vy and Vz, the pilot's operating AP and the quasi-static airplane parameters PA (mass, center of gravity, Vtas, Vcas, angular velocity);
The computer 44 determines the flight control surface command to be applied based on the angular velocity and the angular acceleration, and the aircraft control law 45 uses the quasi-static aircraft parameters PA (mass, center of gravity, Vtas, Vcas, angular velocity).

Depending on the energy desired to obtain the desired measurement distance, the light transmitter allows a very short pulse (eg, on the order of 10 nanoseconds) to be transmitted to the laser 30.
Because of the low wavelength, the laser beam used is preferably in the near ultraviolet, allowing good signal quality to be obtained.

The output beam 11 is then separated by a rotating mirror and prism system 33.
This system 33, as shown in FIG. 5, transmits a beam 50 onto a prism 51 by mirrors 52, 53 and 54 and scans the output beam in one direction differently from four possible directions. The speed is measured according to four directions at an angle of +/− α ° with respect to the plane axis Ox. The greater the angle, the greater the accuracy. For example, 10 ° is selected. It is decided to use a new direction every 15 ms. A full rotating ABCD therefore takes 60 ms.

  The light then passes through the telescope 34, preserving a beam with a very low divergence (on the order of 1 mrad). This beam then enters the atmosphere through a window 46 that has been processed to have a high transmission coefficient for the selected wavelength.

  The transmitted beam 11 collides with atmospheric particles and molecules located on the path. Part of this signal is then scattered back (beam 12) and returned by the telescope 34. The obturator 32 is included in a time volume between 2d / c and 2 (d / c + τ), where d is the desired distance, c is the speed of light, and τ is the duration of each pulse. Only data can be restored.

  In the optical receiver, the data included in the beam 12 is separated into 15 ms packets according to a specific direction.

  The beam received at this time passes through the optical fiber 35 so as to enter the receiving unit.

  This receiving unit constitutes a data processing core. The data processing core consists of a Fabry-Perot interferometer 36, which makes it possible to create an interference circle. For example, an image detector 40, such as a CCD camera, can then cover dimensional variations of different circles associated with variations in wind speed upstream of the airplane.

  The first algorithm processes data regarding the variation in circle diameter resulting from these raw images. Other parameters internal and external to the laser system (temperature, transmit power, telescope position with respect to the aircraft) are also needed to calculate the value of the wind relative velocity component. The data processing system is thus described in reference [5].

  These velocity components are then transmitted to the airplane computer 42. It includes data regarding the pilot's action AP and the current state of the airplane (eg, load factor, airplane angular velocity, etc.). The second algorithm then determines the velocity data obtained from the first algorithm and the plane data that determines the amplitude of the turbulence encountered (Tas or “true air velocity”, pilot command, load factor (mainly nz)). Is used.

  This second algorithm “subtracts” the speed induced by the mechanical movement of the airplane's flight from the speeds Vx, Vy and Vz, and minimizes the airplane response and applies the load according to the choice made. Allows you to develop flight control surface commands that allow you to reduce.

  This second algorithm can be used in open loop or closed loop with some modifications as shown in FIGS.

1) Open loop:
In this case, as shown in FIG. 3, the theoretical turbulence data is obtained from the flight control surface 16 of the airplane 14.
Used to give instructions. There is no feedback due to the inertia or wind speed data of the airplane 14.

  To provide an example, consider an cruising airplane with nz = 1 g and a known Vtas speed. The rider measures the speed V, which is equal to Vtas or cannot reach Vtas. If there is a vertical wind Vzvent, we have Vzvent = Vzalgo (Vz algorithm) −Vztas. This vertical wind affects the lift, incidence and load factor of the aircraft.

  The second algorithm makes it possible to minimize the impact of this wind on the airplane after calculating the wind velocity component.

  To do this, flight control instructions are given.

  In this embodiment, the flight control surface is deflected by an angle X °. This angle X ° makes it possible to predict the wind effect on the airplane. In its simplest form, a command given to an open loop flight control surface may have the following form:

2) Closed loop:
In this case, as shown in FIG. 4, we use all of the necessary sensors 13 present on the plane to fly with respect to the wind component provided by the rider given to the flight control surface 16 as well as the behavior of the plane. Data based on the influence of instructions given to the control surface 16 is used.

  Even without the assumption of simplification and without taking into account the three components of the wind, the command given to the flight control surface can take the following form.

here,
ω is pulsation,
δp is the deflection angle of the roll control surface,
δg is the deflection angle of the pitch control surface,
δr is a deflection angle of the yaw control surface, and nx, ny, and xz are load coefficients based on X, Y, and Z.

The various coefficients kii may or may not include actuation logic based on the desired purpose.
The matrices K1 and K2 (3 × 3 matrix) may include actuation logic and delay circuits.

  What has been presented herein is illustrative and the description can be extended to other aspects and control types. Although specific terms are used herein, this is for the purpose of explanation and has been done so for a limited purpose.

[References]
[1] "Les avions de transport modernes et futures" by (Peyrat-Armandy, A, Teknea, pages 315-325, 1997).
[2] "Coherent lidar turbulence measurement for gust load alleviation" by D. Loreide, RK Bogne, LD Ehernberger, H. Bagley (NASA-TM-104318, August 1996).
[3] “Imaging techniques and systems: riders” by PS Argall, RJ Sica (Encyclopedia of Imaging Science and Technology, J. Hornak, New York, Wiley 869-889, 2002). [1]
[4] International Application Publication No. 2004/003626 Pamphlet
[5] German Patent No. 10316762
[6] US Pat. No. 6,601,801

It is a figure which shows the system of this invention provided in the aircraft. FIG. 2 is a diagram illustrating various flight control surfaces of an aircraft. It is a figure which shows the working principle of the system of this invention. It is a figure which shows the working principle of the system of this invention. It is a figure which shows the scanning system of the system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rider 11 Light beam 12 Laser beam 13 Sensor 14 Aircraft 15 Flight control computer 16 Flight control surface 20 Wing 21 Tip edge flap 22 Rudder 23 Elevator 24 Spoiler 25 Flap 30 Laser 31 Frequency multiplier 32 Obturator
33 Rotating mirror and prism system 34 Telescope 35 Optical fiber 36 Fabry-Perot interferometer 37 Optical lens 38 Filter 39 Image intensifier 40 Image detector 41 Processing element 42 Airplane computer 43 Speed 44 Computer 45 Airplane control law 46 Window 50 Beam 51 Prism 52, 53, 54 Mirror AP Pilot action PA Quasi-static flight parameters Vx, Vy, Vz Wind velocity component Vx *, Vy *, Vz *
ABCD full rotation α Direction with respect to airplane axis Ox

Claims (6)

Predict and measure turbulence upstream of an aircraft, in a system located on board the aircraft,
A rider for transmitting a light beam toward the front of the aircraft and receiving the scattered light beam;
A direct detection device associated with the control means;
A first processing element using a first internal correction algorithm;
And a second processing element that uses a second external correction algorithm to transmit executable instructions to at least one aircraft control surface actuator.   The system of claim 1, wherein the rider is an ultraviolet rider.   The system according to claim 1, comprising an optical transceiver and a receiver. The optical transceiver is
A laser (30);
An obturator (32);
A rotating mirror and prism system (33);
-Telescope (34);
A window processed for a selected laser frequency;
A system according to claim 3, characterized in that it comprises an optical fiber (35).   System according to claim 4, characterized in that it comprises a frequency multiplier (31) at the output of the laser (30). The receiving unit is
A Fabry-Perot interferometer (36) placed between the two optical lenses (37);
A filter (38);
An image intensifier (39);
4. System according to claim 3, characterized in that it comprises an image detector (40) and a processing element (41) for executing a first algorithm.

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